Interrupter



June 12, 1923. 1,458,729

B. D. SAKLATWALLA ET AL I NTERRUPTER Filed April 24, 1919 WITNESSES I INVENTORS Patented June 12, 1923.

PATENT OFFICE.

UNITED STATES BYRAMJ'I D. SAKLATWALLA AND ARTHUR N. ANDERSON, OF GRAFTON, PENNSYL- VANIA, ASSIGNORS, BY MESNE ASSIGNMENTS, T VANADIUM CORPORATION OF AMERICA, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE.

INTERRUPTER.

Application filed April 24, 1919. Serial No. 292,284.

To' all whom it may concern:

Be it known that we, BYRAMJI D. SAKLA- TWALLA, a subject of the British Empire, residing at Grafton, in the county of Allegheny and State of Pennsylvania, and AR- THUR N. ANDERSON, a citizen of the United States, residing at Grafton, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Interrupters, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings, forming part of this specification,in which Figure 1 is a perspective view showing the mechanical construction of the interrupter switches, and

Figure 2 is a vertical section through the solenoid of one of the interrupter switches.

The present invention relates to an electric motor control, and more particularly to a control for preventing the motor from running past the position in which it is desired to have it stop. The present invention is intended for embodiment in a control for the electric motors which regulate the position of the electrodes .in an electric furnace and will be described with particular reference thereto, although it is to he understood that the motor control is not limited to such applications, but may be applied to electric motors used for other purposes.

Referring'to the drawings, 10 and 11 represent motor switches to which the stop motor drift mechanism of the present invention is applied, the switch 10 having contacts 8 and 13, which are adapted to be connected respectively to leads extending to an electrode operating motor, and contacts 15 and 21 which are adapted to be connected through suitable leads to the bus bars which supply the current to said motor. The switch 11 has two contacts 9 and 14 which are adapted to be connected respectively to said motor leads and contacts 16 and 22 which are adapted to be connected with said bus bar leads.

The contacts 8 and 13 of the switch 10 are formed on the ends of two rocker arms 90 and 91 which are yoked together by a crosspin 92 and are rotatably mounted on a stationary shaft 93. The rocker arms 90 and 91 are continuously rocked by means of an eccentric 94 connected by the link 95 with the crosspin 92. The eccentric 94 carried on a shaft 96 which is continuously driven by a motor 97 The contacts 15 and 21 of the switch 10 are mounted on rocker arms 100 and 101 which are yoked together by a crosspin 102. The rocker arms 100 and 101 are rotatably mounted on the bar 93 and are arranged to be moved forward as viewed in F igure 1, by means of the solenoid magnet 24. The rocker. arms 90, 91, 100 and 101, with their contacts 8, 13, 15 and 21 are all insulated from each other and y from the bar 93.

The structure of the magnet 24 is shown in Figure 2. It com-prises a solenoid winding 110. Movable in the solenoid coil is an iron plunger 111 carried on the rod 112 which is connected with the crosspin of the switch. The lower end of the rod 112 carries an adjustable nut 113 which is brought against the stop 114 to limit the upward movement of the plunger 111. The structure of the switch 11 is the same as that of the switch 10. The contacts 9 and 14 are mounted on rocker arms 120 and 121 which are carried on the bar 93 and are arranged to be continuously rocked through the cocentric 124 on the motor driven shaft 96. The other contacts 22 and 16 are carried on rocker arms 130 and 131 which are connected by a cross pin 132 and through the rod 112 with the plunger of the solenoid magnet 25 of the same structure as that of the magnet 24 shown in Figure 2. The rocker arms and contacts of the switch 11 are insulated from each other.

The operation of the motor stop lift mechanism just described is as follows:

The motor 97 runs continuously to rock the contacts 8, l3, 9 and 14 back and forth. Suppose that the magnets 24 and 25 are operatively connected to a Kelvin balance in a control for the electric motor, already 'referred to, which regulates the position of an electrode in an electric furnace, the arrangement being such that when the wattage falls below a certain predetermined value, the magnet 24 is energized, and when said wattage rises above said value, the magnet 25 is energized. When the Kelvin balance is in its neutral position, the magnets 24 and 25 are both deenergized allowing the magnet plungers 111 to fall and pulling the rocker arms backward and downward. The contacts 15, 21, 16 and 22 of the switches 10 and 11 are drawn back out of the path of the rocking contacts 8, 13, 14 and 9, so that no current is fed to the electrode operating motor.

Suppose, however, that the wattage consumed by the furnace electrode falls below the predetermined amount for which the Kelvin balance is set. The Kelvin balance will thereupon be operated to complete the circuit through the solenoid magnet 24 and raise its plunger 111. The contacts 15 and 21 are now in the path of the rocking contacts 8 and 13 which will be brought against the contacts 15 and 21 upon each upward movement of the eccentric 94. When the respective contacts are pushed against each other by the eccentric. the rocker arms 100 and 101 are pushed backwardly, the plunger 111 being yieldingly pushed down against the upward magnetic pull of the solenoid. The time of engagement between the contacts of the switch for each rotation of the eccentric 91 may be varied by adjusting the nut 113. If the nut 113 is turned up the rod 112, the contacts 15 and 21 will be drawn backwardly and the time of engagement of the contacts 8 and 13 therewith shortened. The switch 10 therefore serves as a make and break device to interrupt the feed circuit of the electrode motor, thereby supplying intermittent current pulses to drive the motor. These intermittent current pulses move the motor intermittently and serve to feed the electrode in a step by step movement. The nut 113 is adjusted to vary the length of the current pulses so that the motor rotor will have time to become practically stationary between successive current impulses. This prevents the motor from overrunning or drifting past the position in which it is de sired to have it stopped when the Kelvin balance resumes its normal position to stop further feed of the electrode. The motor comes to rest between the successive feed steps and consequently, does not have sufficient momentum to overrun subsequent steps, so that when the Kelvin balance resumes its neutral position the electrode cannot be fed forward more than a fraction of a step. The intermittent feeding of the current to the electrode regulating motor permits a strong energizing current to be used which insures a positive action of the motor, but at the same time prevents the motor and its associated moving parts from acquiring enough momentum to overrun the desired stopping position.

Th action of the switch 11, when the Kelvin balance operates upon an increase of Wattage, is similar to that described for the switch 10, the electrode motor being fed with an intermittent feed current to raise the electrode step by step.

The frequency of interrupting the motor feed circuit may be varied by adjusting the speed of the eccentric operating motor 97. By adjusting the speed of the motor 97 and the position of the nut 113 to suitably vary the time of engagement of the switch contacts, the length of the steps of the electrode feed may be varied at will by the operator.

While the device herein described for preventing the motor from ovc'rrunning its dcsired stopping position has been illustrated with particular reference to its application to motors for feeding electrodes of an electric furnace, it is to be understood that the invention is not so limited, but may be employed in connection with motors for other purposes and in other structures within the scope of the invention as defined in the following claims.

VVe claim:

1. An interrupter for an electric circuit, comprisinga contact mounted on a rocker arm and means for continuously rocking said arm, and a second contact normally out of the path of movement of the first contact. and an electromagnet for moving the second contact into position to be struck by the first contact, substantially as described.

2. An interrupter for an electric circuit, comprising a contact mounted on a rocker arm, and means for continuously rocking the arm. a second contact normally out of the path of movement of the first contact and means for bringing the second contact into the path of movement of the first contact so as to be struck thereby and to yield when struck, comprising an electromagnetic solenoid and plunger, substantially as described.

3. An interrupter for an electric circuit, comprising two contacts, means for continuously moving one contact so as to intermittently strike the second contact when in its path of movement, and means for moving the second contact into and out of the path of movement of the first contact, substantially as described.

1. An interrupter for an electric circuit, comprising a contact, means for movin the contact continuously back and forth, a second contact normally out of the path of movement of the first contact, and means for bringing the second contact into the path of movement of the first contact so as to be intermittently struck thereby to intermittently make and break the circuit, substantially as described.

5. An interrupter for an electric circuit, comprising a rocker arm, a contact mounted on the rocker arm, and means for continuously rocking said arm, a second contact normally out of the path of movement of the first contact, and means for bringing the second contact into position to be intermittently struck by the first contact due to its rocking motion, substantially as described.

6. An interrupter for an electric circuit,

comprising a contact, means for moving the contact back and forth, a second contact normally out of the path of movement of the first contact, and yielding means for bringing the second contact into the path of back and forth movement of the first contact so as to be struck thereby, the second contact yielding when struck by the first contact, substantially as described.

7. An interrupter for an electric circuit, comprising a contact, means for moving the contact back and forth, a second contact normally out of the path of movement of the first contact, yielding means for bringing the second contact into the path of back and forth movement of the first contact so as to be struck thereby, the second contact yielding when struck by the first contact, and

means for adjusting the amount of yielding of the second contact, substantially as described.

8. An interrupter for an electric circuit, comprising two contacts, means for continuously moving one contact so as to intermittently strike the second contact when in its path of movement, said second contact being normally out of the path of movement of the first contact, means for bringing the second contact into the path of movement of the first contact, and adjusting means for varying the time of contact between the contacts, substantially as described.

In testimony whereof, we have hereunto set our hands.

BYRAMJ I D. SAKLATVVALLA. ARTHUR N. ANDERSON. 

